Vacuum operated sheet feeding mechanism for newspaper inserter

ABSTRACT

A feeding mechanism for single or multi-page sheets of flexible material combines a vacuum operated gripping assembly for initially gripping the lowermost sheet in an inclined stack thereof with a mechanical conveying unit for receiving the lowermost sheet from the assembly and delivering the same to a remote station therefrom. Grippers of the assembly are oscillated through an arcuate path during substantially vertical reciprocation of the carriage carrying the unit and the assembly such that a marginal portion of the sheet held by the grippers is bent away from the stack without moving the remaining portion of the sheet and introduced between opposed delivery elements of the unit for withdrawing the entire sheet from the stack. The grippers are retracted as the sheet is received between the elements, and a vacuum system associated with the assembly actuates the gripper in timed response to the reciprocation of the carriage and extension and retraction of the grippers.

United States Patent Glaser [15 1 3,658,3W [451 Apr. 25, 1972 [22]Filed:

[54] VACUUM OPERATED, SHEET FEEDING MECHANISM FOR NEWSPAPER INSERTER[72] Inventor:

[73] Assignee: Diddle-Glaser, lnc., Emporia, Kans.

[21] Appl.No.: 866,230

Donald A. Glaser, Emporia, Kans.

' [52] US. Cl. ..271/29, 271/14, 27l/DlG. l

[51] lnt.Cl. 58] Field of Search...

..B65h 3/10, B65h 5/04 ..271/29, 27, 14, ll, 12

Primary Examiner-Even C. Blunk Assistant Examiner-Bruce H. Stoner, Jr.Attorney-Schmidt, Johnson, Hovey, Williams & Chase [57] ABSTRACT Afeeding mechanism for single or inulti-page sheets of flexible materialcombines a vacuum operated gripping assembly for initially gripping thelowermost sheet in an inclined stack thereof with a mechanical conveyingunit for receiving the lowermost sheet from the assembly and deliveringthe same to a remote station therefrom. Grippers of the assembly areoscillated through an arcuate path during substantially verticalreciprocation of the carriage carrying the unit and the assembly suchthat a marginal portion of the sheet held by the grippers is bent awayfrom the stack without moving the remaining portion of the sheet andintroduced between opposed delivery elements of the unit for withdrawingthe entire sheet from the stack. The grippers are retracted as the sheetis received between the elements, and a vacuum system associated withthe assembly actuates the gripper in timed response to the reciprocationof the carriage and extension and retraction of the grippers.

' 10 Claims, 13 Drawing Figures PATENTEDAPR 25 I972 SHEET 1 [1F 4 f7TTORN E Y5.

VACUUM OPERATED SHEET FEEDING MECHANISM FOR NEWSPAPER INSERTER Thisinvention relates to machines for handling sheets of flexible materialand, more particularly, to a device for successively feeding single ormultiple sheet newspaper sections from an inclined stack thereof to adelivery station or to an awaiting preopened newspaper for insertionthereinto.

A single edition of a metropolitan newspaper, especially a Sundayedition; generally consists of a number of different sections relatingto various fields of interest such as world and local news, sports,social news, or the like. Several of the sections are generally printedin advance of the other sections and must thereafter be brought togetherfrom their individual printing locations and assembled in propersequence to form a completed edition of the paper. A convenient means ofaccomplishing this final assembly of the edition has been effected byproviding a number of side-by-side, interconnected assembling unitswhich successively deliver the individual sections from stacks thereofat one end of the units into the awaiting, constantly moving opensections of the newspaper at the other end.

In addition to assembling the various sections of a newspaper edition,there has been an increasing need to provide machines of the above typewhich are adapted for stuffing the newspaper edition with specialinserts, such as coupons, TV guide sections, and various types ofadvertisement sections. In many instances, inserts of this type areprinted well in advance of printing of the main edition and areoftentimes printed in separate localities. Therefore, the problem ofeconomically assembling the assorted sections and the inserts is onceagain presented. This problem is also apparent in the instance of ametropolitan newspaper having territorial sections which must becollated with common, city-wide sections at various localities aroundthe city.

Newspaper sections present special handling problems in view of themultiple-page nature of each section and the common practice ofconveniently storing the sections in upright stacks. Numerousengineering problems have been encountered in designing machines whichwill reliably remove successive sections from the top of such stacks.Bottom delivery systems are generally preferable since they eliminatethe need for continual readjustment of the stack level as required intop delivery systems, but the weight of the stack above the lower endsection thereof and the problem of access to the end section createproblems with this system also.

Vacuum-operated feeder mechanisms have experienced some difficulties incoping with the problems of multiple pages, stack weight, andinaccessibility. Once contact has been made with the end section of thestack, sufficient vacuum pressure to the newspaper grippers must besupplied in order to insure that all pages of the section arecontrolled. Further, the system must be sufficiently strong to efiectwithdrawal of the section from the stack against the weight of thesections thereabove. Tilting the stack has alleviated these problems toa certain degree, although not to a sufficient extent to providereliable feeding and delivery of each section.

The above problems may be overcome by the utilization of a feedingsystem which employs a vacuum assembly to initially grip a marginalportion of the end section and, without actually withdrawing thesection, to bend the gripped portion and introduce the same into amechanical conveying unit for delivery to awaiting newspaper sections.Since the vacuum pressure is not utilized to shift the end sectionagainst the weight of the stack, high vacuum pressure is not necessaryand the multiple page nature of the sections presents no problem.

Accordingly, it is an important object of the present invention toprovide mechanism for feeding successive single or multiple sheetnewspaper sections, inserts, or the like, from a stack thereof to aremote station which eliminates the necessity for sensitive highpressure vacuum systems or complex mechanical structure for effectingthe initial withdrawal of each section from the stack.

Another important object of the invention is to provide a feederincorporating a vacuum gripping assembly for initially gripping amarginal portion of the end section without shifting the section fromthe remainder of the stack, and for introducing the gripped portionbetween opposed rollers of a mechanical conveying unit to effectwithdrawal of the section from the stack and subsequent delivery thereofwith speed and reliability to a remotestation. In this respect, animportant aim of the present invention is to provide positive grippingaction effected by oscillating vacuum grippers which assume zerorelative speed during initial engagement with the portion of the endsection.

A further important object of the present invention is to provide afeeder as aforesaid which is designed such that a minimum of set-up timeprior to operation thereof is required, and whose operating parametersmay be readily adjusted in timed relationship to the rotation of acommon drive shaft for all operating units of the feeder.

Yet another object of the instant invention is to provide a feeder asaforesaid which will reliably handle sheet material of various lengths,widths, and thicknesses.

In the drawings:

FIG. 1 is a side elevational view of a machine having a feeder whichembodies the principles of the present invention, the delivery carriagethereof being shown at the beginning of an operating cycle in its raisedposition for the initial gripping of a sheet of flexible material suchas a newspaper section;

FIG. 2 is a fragmentary, side elevational view of the feeder of FIG. 1showing the delivery table halfway through an operating cycle anddisposed in its lowered position after bending the portion of the endsheet and immediately preceding the withdrawal thereof from the stack;

FIG. 3 is a top plan view of the feeder with the operating parts thereofbeing shown at the beginning of an operating cycle corresponding totheir positions in FIG. 1;

FIG. 4 is a fragmentary, side elevational view similar to FIG. 1 showingthe opposite side of the feeder;

FIGS. 5 and 6 are enlarged, fragmentary, cross-sectional views takensubstantially along lines 5-5 and 6-6 of FIG. 3;

FIG. 7 is an enlarged, exploded view showing the relationship betweencomponents of the valve apparatus for the vacuum lines;

FIG. 8 is an enlarged, fragmentary, cross-sectional view taken alongline-8--8 of FIG. 3;

FIG. 9 is an enlarged, fragmentary, cross-sectional view taken alongline 9-9 of FIG. 1;

' FIG. 10 is an enlarged, fragmentary, cross-sectional view taken alongline 10-10 of FIG. 9;

FIG. 11 is an enlarged, fragmentary, cross-sectional view taken alongline 1111 of FIG. 5;

FIG. 12 is an enlarged, fragmentary, cross-sectional view taken alongline 12-12 of FIG. 5; and

FIG. 13 is an enlarged, fragmentary, cross-sectional view similar toFIG. 12, but showing the retractable gripper unit in its sheet-releasingposition.

FIGS. 1 and 3 show a machine employing the feeding mechanism 20 whichbasically includes a receptacle unit 22 for receiving and supporting aninclined stack of newspaper sections or the like, a vacuum-operatedgripping assembly 24 adjacent the receptacle unit 22 for initiallygripping and bending a portion of the end newspaper section in thestack, a conveying unit 26 for receiving the gripped portion of thenewspaper section from the gripping assembly 24 and withdrawing thesection from the stack, and an inclined shelf 25 for receiving thesections delivered thereto by conveying unit 26. It is to be understoodthat the shelf 25 is representative of various alternative structureswhich could be provided in this location for use with feeder 20 such asconveyor structure for moving opened newspapers past feeder 20 or othersupport structure for reforming a stack of the fed newspaper sectionsafter counting thereof or the like.

A pair of spaced, upright support plates 28 and 30 having downwardlyextending slots 28a and 30a respectively are held apart by a transversecenter brace 32, and as one function, serve to support the receptacleunit 22 at the supply end of the feeder 20. The receptacle unit 22includes an inclined platform 34 spanning the distance between thesupport plates 28 and 30 and rigidly mounted thereon by suitable boltmeans (not shown). A support table 36 having a pair of depending sideplates 38 is shiftably carried on the upper surface of the platform 34by two sets of opposing rollers 40 on each of the side plates 38 whichengage opposite surfaces of platform 34 (FIG. Each of the side plates 38projects through an elongated slot 42 in platform 34 and is connected toa chain 44 trained over a sprocket 46 which is carried by a transverseshaft 48 joumaled by the support plates 28 and 30. The other end ofchain 44 hangs freely from sprocket 46, and the transverse shaft 48projects through the support plate 30 and rigidly receives a worm gear50 which intermeshes with a worm gear 52. Rotation of the gear 52 by theknob 54 at the outer end thereof regulates the level of the table 36 toproperly position the stack supported thereon.

A pair of elongated, adjustable stack guides 56 engageable with thesides of the stack are individually supported by a pair of shafts 58through the support plates 28 and 30 respectively. A pair of bearings 60rigid to the plates 28 and 30 respectively, journal each of the shafts58, and hand setscrews 62 through each of the bearings 60 are disposedfor engagement with the corresponding shaft 58 to limit the lateraladjustment of the guides 56. Each of the guides 56 is provided with anupright rod 64 having an adjustable brace unit 66 adjacent the outer endthereof which is engageable with the end section of the stack to bracethe upper margins thereof against untimely bending into the grippingassembly 24.

As earlier described, it is contemplated that machines employing feederssuch as feeder may be arranged in a straight line in side-by-siderelationship in the instance where several different sections or insertsare to be assembled into the final edition of the newspaper.Accordingly, with such an arrangement, it is convenient to drive themachines from a single prime mover and provide a common drive shaft or,altematively, individual shafts for each feeder which may beinterconnected to form a common drive element, such that the operatingcycles of the aligned feeders may be regulated in a timed relationshipto one another. Thus, a power drive shaft 68 for feeder 20 extendsbetween the support plates 28 and 30 projecting outwardly from thelatter and rigidly carrying a drive sprocket 70 on the end thereof. Anendless drive chain 72 is trained about the drive sprocket 70, a largesprocket 74 on the outside of plate 30, and a third sprocket 76, thesprockets 74 and 76 thus being driven by the rotation of shaft 68 and,in turn, effecting the operation of the gripping assembly 24 andconveying unit 26 as will hereinafter be described. An idler sprocket 78is carried by plate 30 and engages the chain 72 intermediate thesprockets 74 and 76.

As best seen in FIG. 9, the sprocket 74 is keyed to a shaft 80projecting through a hole in plate 30 and is joumaled by a bearing 82secured to the inner face of the same and a bearing 84 disposedapproximately centrally of the plates 28 and 30 and secured to thecenter brace 32. A portion of the shaft 80 extends beyond bearing 84 andcarries a crank assembly 86 including a wheel 88 and a generally uprightdrive rod 90 eccentrically connected to the wheel 88 through bearingstructure 92. The drive rod 90 is tubular at its marginal ends, thelower end thereof threadably receiving a fastener component 94 connectedto bearing structure 92 to provide for longitudinal adjustment of driverod 90.

The. upright drive rod 90 is pivotally coupled to the main feedercarriage 96 (FIG. 6) for oscillating the latter between raised andlowered positions thereof upon rotation of the main shaft 80. Thecarriage 96 includes a flat frame member 98 extending practically thedistance between support plates 28 and 30, a pair of spaced-apart endplates 100 bolted to opposite ends of the frame member 98, and threespaced-apart, elongated guide plates 102 of formed sheet material whichoverlie the frame member 98 and are rigidly fastened thereto between endplates 100. The carriage 96 is supported at one end by a driven shaft104 (FIG. 8) which extends between the support plates 28 and 30 joumaledby bearing sets 106, through the table end plates joumaled by suitablebearings I08, and projects through support plate 30 to carry thesprocket 76. A coupling block (FIG. 6) bolted centrally of the framemember 98 carries a short pivot pin 112 which is coupled to an eye 114adjustably threaded into the upper end of drive rod 90.

Most components of the conveying unit 26 are mounted on the carriage 96and include a pair of spaced-apart sheaves 116 (FIG. 8) pinned on theshaft 104 for rotation therewith and each carrying an endless belt 118which couples with other conveying components at the opposite end of thecarriage 96 as will hereinafter be described. It may be seen that thesheaves 116 are aligned with the spaces between adjacent guide plates102, and that the belts 118 are substantially flush with the uppersurfaces thereof or extend slightly thereabove for gripping thenewspaper sections as they travel along their paths of delivery. A pairof upstanding, U-shaped support brackets 120 mounted on respective endplates 100 pivotally support a pair of rocker arms 122 which extendrearwardl y of carriage 96 and carry a rigid shaft 124 therebetween. Thereduced, opposed ends of shaft 124 are rigidly held by suitablesetscrews or the like to prevent relative rotation of shaft 124.

A pair of freewheeling rollers 126 are mounted on shaft 124 for rotationthereabout in direct alignment above the belts 118. A spring-loadedhold-down assembly 128 (FIG. 6) is provided on each of the rocker arms122 to bias the rollers 126 into engagement with the belts 118 forming anip therebetween for the reception of newspaper sections. Each of thehold-down assemblies 128 includes a threaded element 130 which extendsthrough the corresponding rocker am 122 and is threadably received bythe corresponding end plate 100. A coil spring 132 about the element 130engages the top of the rocker arm 122 and is maintained in a compressedcondition by a knob 134 threaded onto element 130.

The carriage end plates 100 carry bushings 136 at the forward endsthereof which serve to journal opposite ends of a tubular shaft 138(FIG. 5). Three freely rotatable paper-engaging rollers 140approximately the same diameter as or slightly larger than belts 118 aremounted on the shaft 138 for rotation thereabout and project into cutoutportions 102a of the respective guide plates 102. The shaft 138 alsosupports a pair of spaced-apart bearings 142 which carry sheaves 144about which the ends of the belts 118 are trained.

The tubular shaft 138 comprises an important part of the grippingassembly 24 as well as of the conveying unit 26 as will hereinafterbecome clear, and is actuated for oscillation in opposite, timedrelationship to the reciprocation of the carriage 96 by a power crankassembly 146 (FIG. 5). The assembly 146 comprises a hollow stub shaft148 bolted to the support plate 28, an elongated crank arm 150 pivotallycoupled to the stub shaft 148 and extending generally upwardlytherefrom, and a clamping link 152 eccentrically pinned to the upper endof arm 150 and having a pair of jaws which firmly grip the adjacent endof the shaft 138.

The conveying unit 26 further includes a pair of rocker arms 154 (FIGS.5 and 6) pinned to the respective support brackets 120 which extendtoward the forward or elevated end of carriage 96. Each forward rockerarm 154 rigidly receives a reduced end portion of an elongated shaft 156spanning the distance therebetween which supports a pair of spacedbearings 158 carrying freely rotatable rollers 160 in alignment abovethe conveying belts 118. A pair of spaced-apart, curved, upper paperguides 162 are secured between the shafts 156 and 124 above the guideplates 102 and extend substantially the lengths thereof. The shaft 138also carries a pair of cams 164 securely clamped thereon by a retainingscrew 166 (FIG. 11), each of the cams 164 being disposed between aroller 140 and the adjacent carriage end plate 100. A pair of spaced camfollowers 168 are pivotally mounted on adjacent ends of the shaft 156 inalignment above the respective cams 164. The followers 168 are normallybiased in a counterclockwise direction viewing FIG. 11 by coil springs170 about the shaft 156 which are retained thereon by spring retainers172. A nylon stop 174 behind each of the followers 168 is engageabletherewith and is disposed to limit the counterclockwise biasing of thesame to the position shown in FIG. 11. A pair of springloaded hold-downassemblies 176 at opposite sides of the carriage 96 on forward rockerarms 154 respectively normally bias the rollers 160 on shaft 156 intoengagement with the belts 118 and comprise components identical to thoseof the rear hold-down assemblies 128.

As mentioned above, the tubular shaft 138 is an essential component ofboth the conveying unit 26 and the gripping assembly 24, and its role aspart of the gripping assembly 24 will now be described in more detail. Aplug 178 threaded into the openleft end of the tubular shaft 138 viewingFIG. 5 serves to close the passage 180 therethrough. Four sucker orgripper units 182 are mounted on shaft 138 at spaced intervalstherealong and project outwardly therefrom beyond belts 118 as showngenerally in FIGS. 3 and 5 and in detail in FIGS. 12 and 13. Referringmore particularly to FIGS. 12 and 13, each of the gripper units 182comprises an elongated plunger 184 extending through the shaft 138 atright angles thereto and having a central, longitudinal bore thereinextending from the leading end to approximately the midpoint thereof.Two cross bores through the plunger 184 collectively denoted 188intersect at the longitudinal bore 186 and communicate the same with thepassage 180. A flexible, preferably rubber sucker cap 190 is provided atthe outer end of each plunger 184, and an enlargement 192 is removablysecured to the opposite end thereof. L-shaped cam fingers 194 areadjustably fastened to the underside of frame member 98 by a pair ofmounting screws 196 which extend through enlarged holes in the dependingfingers 194. A coil spring 198 about plunger 184 between the enlargement192 and shaft 138 biases the enlargement 192 and hence plunger 184rearwardly toward the cam finger 194 shown in engagement withenlargement 192 in FIG. 12, and a shoulder 199 rigid to plunger 184between the sucker cap 190 and shaft 138 limits the retracting motion ofthe gripper unit 182 as it engages the surface of shaft 138 illustratedin FIG. 13. It may be seen viewing FIGS. 12 and 13 that gripper unit 182in FIG. 13 has been rotated approximately 100 to 1 from the position ofFIG. 12, and accordingly, in the position of FIG. 13 the gripper unit182 is free to retract from the extended position of FIG. 12.

The vacuum system which operates to actuate the gripper units 182includes a vacuum line 200 adapted to be connected to a suitable vacuumpump (not shown), the tubular shaft 138 of gripping assembly 24, andvalve apparatus broadly denoted 202 disposed intermediate the shaft 138and line 200 which is responsive to the reciprocation of the carriage 96to open and close line 200 in timed relationship to the oscillation ofthe gripper units 182. The valve apparatus 202 includes a circularmember 204 secured to the right carriage end plate 100 and has a centralbore 206 which receives the shaft 138 so as to dispose bore 206 inalignment with the passage 180 through shaft 138. Apparatus 202 furtherincludes a circular valve component 208 secured to the outer face ofmember 204 by a pair of spring-loaded bolts 210 which operate tomaintain the component 208 in alignment with member 204, but permit theshiftable insertion of a control plate component 212 therebetween. Thecontrol plate 212 is pivotally bolted to the right end plate 100 througha large hole in plate 30 by a bolt 214, and is provided with anelongated clearance slot 216 (FIG. 7) for clearing one of the bolts 210.Plate 212 is also provided with a substantially horizontal, smallerelongated opening 218 which, with the gripper assembly 24 in theposition illustrated in FIG. 5, is in alignment with a similar elongatedopening 220 which extends inwardly from the back face of component 208into a cavity 222 (FIG. 5 within the outer face of the component 208. Acover plate 224 fastened to the outer face of component 208 has afitting 226 therethrough which is adapted to receive one end of thevacuum line 200 whereby to communicate the latter with cavity 222.Additionally, a cross groove 228 is provided in the back face ofcomponent 208 above the opening 220 which does not communicate with thecavity 222, but which instead is disposed to communicate with theatmosphere such that the shaft passage 180 may be exhausted when theopening 218 in control plate 212 is disposed in alignment therewith.

In addition to the valve apparatus 202, a control system denotedgenerally as 230 is provided on the outer face of support plate 30 forregulating the opening and closing of the valve apparatus 202 duringoperation of feeder 20, and for quickly halting the continued operationthereof upon malfunction of either the gripping assembly 24 or conveyingunit 26, such as the failure to pick up and deliver one of the newspapersections. The control system 230 has an L-shaped mounting block 232bolted to the outer face of support plate 30 which serves to supportmost of the components of system 230 including a solenoid 234 secured toblock 232 by an L- shaped brace 235, and a specially configured,elongated blocking member 236 which is pivotally secured to the innerface of mounting block 232 between the latter and plate 30. A suitablesensor structure 238 is mounted on the frame member 98 beneath table 96,and is disposed such that the upper margin thereof is presented abovethe top surface of guide plates 102, hence being engageable withnewspaper sections as the latter pass through the feeder 20. A lowerstop 240 on the outer face of support plate 30 is disposed in alignmentwith the control plate 212 for engaging the lower edge of the latterduring its reciprocation with the carriage 96, and the retractable,spring-loaded solenoid armature 242 nonnally projects through themounting block 232 and serves as an upper stop for the control plate 212as well as a support means beneath the blocking member 236 to preventthe latter from gravitionally swinging beyond its normally raisedlocation.

OPERATION It is to be noted at the outset that all of the figures exceptFIGS. 2, 7 and 13 show the operating components of feeder 20 in positionto begin an operating cycle starting with the gripping of a section fromthe stack. FIGS. 2, 7 and 13 illustrate the feeder 20 at the midpoint ofits operating cycle. Ac-

cordingly, the crank assembly 86 is disposed in its top deadcenterposition such that the drive rod 90 maintains the carriage 96 at itsupper limit of travel. Also at this time, the crank assembly 146 isdisposed to place the gripping assembly shaft 138 in its mostcounterclockwise position viewing FIG. 12 such that the gripper units182 are disposed in their initial newspaper gripping positions.Additionally, it may be seen that the top edge of control plate 212 isabutting the armature 242 of the solenoid with the circular member 204and valve component 208 shifted relative to control plate 212 to disposetheir respective openings 218 and 220 in alignment so as to evacuatepassage and gripper plungers 184.

Initially, a stack of newspaper sections or the like which are to be fedthrough feeder 20 should be placed on table 36 with their folded edgesup. Accordingly, the stack will be inclined at approximately 30 from thehorizontal viewing FIG. 1, and the lowermost section will be flatagainst platform 34 with its upper marginal portion overhanging thesame. If the marginal portion of the section is not then in alignmentwith the sucker caps of the gripper units 182, adjustments may be madeby rotating the worm gear 52 to cause incremental raising or lowering ofthe table 36 along platform 34. Further, it is important to insure thatthe gripper units 182 are extending outwardly far enough to engage themarginal portion. This adjustment may be effected by loosening themounting screws 196 through the frame member 98 and subsequentlyshifting the cam fingers 194 into their proper positions.

Since the vacuum line 200 and passage 180 through shaft 138 is evacuatedat this time, the sucker caps 190 engage the marginal portion of thenewspaper section and firmly retain the same. Clockwise rotation of themain drive shaft 68 viewing FIG. 1 causes further rotation of the shaft80 to shift the crank assembly 86 from its top dead-center position ofFIG. 9.

Rotation of the crank assembly 86 pulls the drive rod 90 downwardly fromits upper position and causes the downward travel of the carriage 96. Asthe carriage 96 begins this movement, the crank assembly 146 causes thevacuum shaft 138 to rotate in a clockwise direction viewing FIGS. 12 and13 such that the gripper units 182 bend the gripped portion about theaxis of shaft 138. Further downward movement of carriage 96 causescontinued clockwise rotation of the gripper units 182, and, since thelongitudinal axis of shaft 138 is continually lowered at the same ratethat the gripper units 182 are being rotated. the gripped portion of thesection is bent about such axis without actually pulling on the sectionitself or moving any part thereof except for that marginal portion whichis gripped by the units 182.

It is to be noted that due to the size differences in the sprockets 74and 76 as well as the relationships of the parts within the feeder 20,the moving parts of the conveying unit 26 are rotated at approximatelytwice the rotational speed of the moving parts of the gripping assembly24 at their greatest speed. Accordingly, as the gripper units 182 arecarrying the gripped portion of the newspaper section in an arcuate pathfor later engagement and delivery by the conveying unit 26, the frontsheaves 144 carrying the conveyor belts 118 are rotating at asubstantially faster speed. Therefore, as the lower face of thenewspaper section engages the free wheeling rollers 140, some lightcontact is made between the belts 118 and the lower face of the section,but due to the high speed of the belts 118 sufficient contact is notmade to disturb the bending action of the section.

Referring particularly to FIG. 11, during the clockwise rotation of theshaft 138 the cams 164 have been simultaneously rotated in the samedirection to effect the actuation of the forward rocker arms 154.Viewing the right cam 164 shown in FIG. 11, it may be seen that as itrotates in its clockwise direction, the cam follower 168 successivelyengages a section of the flat stretch 164a and the curved stretch 164bso as to raise the rocker arms 154 and present a space between therollers 160 and belt 118 to permit reception of the leading marginaledge of the newspaper section.

As the carriage 96 continues to lower and the shaft 138 continues torotate in its clockwise direction viewing FIG. 12, the enlargements 192on the ends of gripper units 182 gradually become disengaged from thecam fingers 194. However, the vacuum pressure through the gripperplungers 184 is preferably strong enough to counteract the force of thecoil springs 198 to maintain the gripper units 182 in their extendedpositions as the marginal portion of the end section is engaged by thesurface of rollers 140. As the carriage 96 approaches its lower limit oftravel, the lowermost edge of control plate 212 nears the lower stop240. The control plate 212 engages stop 240 when the crank assembly 86is approximately 10 from its lowermost position, and each of the gripperunits 182 is substantially at a 12 o'clock position viewing FIG. 12.Although the control plate 212 is prohibited from further downwardmovement by the stop 240, the carriage 96 continues to travel downwardlyas the crank assembly 86 completes its half revolution, and accordingly,the circular member 204 and valve component 208 of the valve apparatus202 continue to move with the carriage 96 relative to control plate 212to begin exhausting the vacuum within passage 180. Downward movement ofthe carriage 96 continues until the cross groove 228 in valve component208 is disposed in alignment with the opening 218 in control plate 212such that the passage 180 is exhausted to the atmosphere with the partsassuming the positions of FIG. 2. At this time, upon loss of vacuumpressure, the gripper units 182 in the 1 oclock position of FIG. 13 areretracted by operation of the coil springs 198 so as to release thegripped marginal portion of the newspaper end section. Immediatelythereafter, the cam follower 168 drops off the arcuate stretch 16412 ofcam 164 into the cavity 164C to cause the rollers 160 to drop instantlydownward and engage the marginal portion between the same and theconveyor belts 118.

As the rollers and conveyor belts 118 engage the marginal portion of thenewspaper section, the section is pulled from the stack and moved overthe guide plates 102 and sensor structure 238 toward delivery to theinclined shelf 25.

As the carriage 96 is caused to move upwardly from its lowered positionshown in FIG. 2 as the crank assembly 86 begins the last half of itsrevolution, the crank assembly 146 causes the shaft 138 and hencegripper units 182 to rotate in a counterclockwise direction viewing FIG.13 with the units 182 being disposed in their retracted positions. Itmay be seen that in this manner, retraction of the units 182 insuresthat no engagement thereof with the newspaper section being withdrawnfrom the stack will be effected, so that steady withdrawal will beaccomplished. Simultaneously, the cam 164 on each end of shaft 138begins to rotate in a counterclockwise direction viewing FIG. 11 suchthat the cam followers 168 tend to climb out of the cavity 164C onto thearcuate stretch 164b thereof. Because of the spring pressure effected bythe retainer spring 172 on each of the followers 168, the followers 168spring outwardly to permit passage of the arcuate stretch 164b andmaintain the rocker arms 154 in their lowered positions such that therollers 160 are continuously down in engagement with the newspapersection. Accordingly, as the shaft 138 is further rotated along with cam164, the followers 168 continue to travel over the arcuate stretch 16412and over the flat stretch 164a until such time as the cam 164 iscompletely rotated to its final position.

As the carriage 96 returns to its upper position, the control plate iscarried therewith while the valve member 204 and component 208 remain inthe position relative to plate 212 as shown in FIG. 12. As the crankassembly 86 nears 10 from its top dead-center position of FIG. 9, thegripper units 182 have once again been presented in their extendedpositions by engagement thereof with the cam fingers 194. Also, as thecontrol plate 212 engages the underside ofsolenoid armature 242, theplate 212 is retained while the carriage 96 and the member 204 andcomponent 208 travel upwardly therewith to begin a new cycle ofactuating the vacuum system. When the member 204 and component 208 havebeen completely shifted and the crank assembly 86 is in its topdead-center position, the openings 218 and 220 are once again inalignment to effect evacuation of the passage so as to once againactuate the gripper units 182.

It may be seen that throughout the one cycle of operation the vacuumgripping assembly 24 was not used to effect withdrawal of the newspapersection, but only to prepare the marginal end portion thereofforsubsequent gripping between the rollers 160 and conveyor belt 118 of theconveying unit 26. Accordingly, the amount of vacuum pressure needed inthis instance to effect the bending of the marginal portion of thenewspaper section is substantially less than that which would berequired if the section were to be completely withdrawn by the grippingassembly 24.

Occasionally, a malfunction of the feeder 20 might occur such as in theinstance where the gripping assembly 24 failed to properly engage thenewspaper section such that no section would be withdrawn from thestack. In this instance it is desirable to stop the operation of thefeeder 20 as well as any additional equipment which might be used todeliver awaiting open newspaper editions at shelf 25. In this respectthe provision of the sensor structure 238 operates to actuate thecontrol system 230 to maintain the vacuum line in its exhaustedcondition for one extra cycle of the gripping assembly 24 as well as topreferably stop the other equipment at the delivery end of the feeder20. For instance, if the feeder 20 has malfunctioned so that a newspapersection does not pass over the sensor structure 238 to depress thelatter, the solenoid 234 may be actuated to withdraw the armature 242thereof as the carriage 96 is disposed in its lower position. Suchwithdrawal of the armature 242 permits the blocking member 236 togravitationally swing into engagement with the valve member 204 when thelatter is disposed in its position relative to control plate 212 asshown in FIG. 2. Thus, as the carriage 96 continues to rise with thevacuum passage 180 being exhausted to atmosphere, the protruding legportion 236a of member 236 (shown best in FIG. 3) serves to block theretracted armature 242 as control plate 212 swings toward its upperdisposition. Accordingly, instead of striking the armature 242 and beingretained thereby, the control plate 212 shifts past the same until thecarriage 96 reaches its upper limit of travel. Thus, no relativeshifting of control plate 212 and component 208 has occurred so that thepassage 180 is still exhausted to the atmosphere through the crossgroove 228.

The control system 230 may be provided with relays or the like whichwill maintain the solenoid 234 in its actuated condition with thearmature 242 being withdrawn until a reactivation switch has beenclosed, but the present embodiment contemplates having the armature 242withdrawn for only one cycle of the feeder 20. Accordingly, the blockingmember 236 is provided with a second leg 236b which is offset to oneside of the leg 236a and crosses over the upper leading edge of controlplate 212 therebelow. It may be seen that the leg 236a disposed on theouter side of control plate 212 adjacent the armature 242 is of such awidth that when in its uppermost position, the leg 236a permits thepassage of the armature 242 beneath the same into engagement with theouter face of the control plate 212 when the solenoid 234 isdeactivated. The armature 242 being in engagement with the face of plate212 has no effect in blocking the same, but as the carriage 96 beginsits downward travel, the armature 242 slips off the surface of plate 212between the space between the latter and member 236 so that the latteris once again held from swinging downwardly. As the carriage 96continues swinging downwardly and control plate 212 is brought intoengagement with the stop 240, the openings 218 and 220 are once againbrought into alignment with one another so as to evacuate the passage180 and provide for the gripping of a new marginal portion of an endnewspaper section from the stack.

It may therefore be seen that the feeding mechanism of the presentinvention provides a rapid, economical, and reliable means of feedinginserts or the like which has heretofore not been available. The featureof bending the marginal portion of the end newspaper section withoutmoving the remainder of the section at that time eliminates thenecessity of having a substantially high-pressure vacuum system.Further, it may be seen that the present feeder may find abundant use injobs other than stuffing newspapers, such as for rapidly counting sheetsand other such operations. In addition, it may be seen that theconstruction of the air valving system for the feeder and the spacialrelationship between the parts thereof and the gripper assembly presenta particular advantage in that the valving of the air is disposedrelatively close to the suckers, thus requiring a minimum volume of airto be evacuated at the point of pick-up. This is a desired advantageover other types of valving systems which usually have to be locatedsomewhere on the machine where actuation can be obtained mechanically,Such remote location of the valving system manifestly causes a greatervolume of air between the valve and the suckers which must beinstantaneously evacuated.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

l. A feeder for flexible sheet material comprising:

a receptacle for receiving and supporting a plurality of said sheets instacked relationship;

a vacuum operated gripping assembly adjacent said receptacle andprovided with a gripper engageable in one position thereof with themarginal portion of an adjacent end sheet of the stack and rotatablethrough an arcuate path of travel into a sheet releasing position tobend said marginal portion of the end sheet away from the stack withoutmoving the remaining portion of the end sheet;

a conveying unit having a pair of opposed, relatively shiftable deliveryelements for receiving a sheet therebetween at said releasing positionof the gripper;

power means connected to said gripper for rotating the same through saidarc; and

mechanism operably coupled to said gripper assembly and the conveyingunit for controlling vacuum pressure to the gripper to cause said onemarginal portion of the end sheet to be gripped thereby at said oneposition of the gripper and to discontinue the vacuum thereto at saidrelease position thereof while actuating the elements in synchronismwith said gripper rotation to effect withdrawal of the end sheet fromthe stack for advancement along a delivery path,

said power means including drive structure operably connected to saidgripper assembly for raising and lowering the latter relative to saidstack,

said power means being operable to oscillate the gripper between thesheet-engaging and sheet-releasing positions thereof during raising andlowering of the gripper assembly by said structure, there being a vacuumline coupled to said gripper and adapted for connection to a vacuumsystem, said mechanism including valve apparatus associated with saidline and operated in response to raising and lowering of said gripperassembly for opening and closing the line,

said valve apparatus including a pair of opposed, relatively shiftablevalve components, one of said components being movable with saidassembly during raising and lowering thereof, the other of saidcomponents being retainable in a stationary disposition while said onecomponent is shifted relative thereto to effect opening or closing ofthe line.

2. The feeder as set forth in claim 1, wherein is provided an actuatablecontrol system associated with said valve apparatus for maintaining thevacuum line in a closed condition upon malfunction of thegrippingassembly, said system including a solenoid adjacent the upper limit ofassembly travel effected by said drive structure and having aretractable plunger normally extended in disposition to engage saidother component and retain the same as said one component continuesmovement with the assembly to open said line, and sensor means connectedto said solenoid and operable to sense malfunction of the assembly andactuate the solenoid to withdraw said plunger thereof to clear saidother component such that the latter is not retained by the plunger andno relative shifting of the components occurs to open said line.

3. The feeder as set forth in claim 2, wherein said control systemfurther includes a blocking member mounted for shifting movementrelative to said solenoid plunger and normally resting thereon, saidmember being disposed for movement into blocking relation with saidplunger and engagement with said valve apparatus upon actuation of thesolenoid to maintain the plunger in a withdrawn disposition such thatsaid other component is not retained by the plunger.

4. A feeder for flexible sheet material comprising:

a receptacle for receiving and supporting a plurality of said sheets instacked relationship;

a carriage rotatably mounted adjacent the receptacle for movement alonga reciprocal path to cause one end of the carriage to move past amarginal portion of one end sheet of the stack thereof;

a tubular shaft rotatably carried by the carriage for pivoting about anaxis parallel with and spaced from the axis of rotation of the carriage;

a series of spaced, vacuum operated hollow grippers carried by the shaftin generally perpendicular relationship thereto and communicating withthe passage through the shaft;

operating mechanism coupled to the carriage and to the shaft forreciprocating the carriage and oscillating the shaft in timedrelationship;

cam means on the grippers and said carriage cooperable to shift thegrippers into extended first positions engageable with the marginalportion of said end sheet of the stack when the carriage is at one endof its path of travel away from the marginal edge of the end sheet andthe shaft is in disposition with the grippers extending therefrom towardthe stack, and to retract the grippers into sheet releasing positions inresponse to movement of the carriage toward the marginal portion of theend sheet and rotation of the shaft through an arc to bend said marginalportion of the gripping position thereof and for discontinuing saidpressure when the gripper is in the sheet-releasing position thereof,

said vacuum line defining said axis of rotation of the .P said me beingsupported for rotation about said axis and having the gripper mountedthereon for rotation sheet gripped by the grippers away from the stackwithout 5 therewfthi l moving the remaining portions ofthe end Sheet; aconyeymg unit associated with said grlppmg assembly and movableconveying means carried by the carriage and posh oscillatable therewithfor completing removal of the end tioned to receive an end sheet removedfrom the stack sheet the and to transfer the removed sheet to a pointremote from said a .rotary emem mounted f i the receptacle; 1O vacuumlmefor rotat on relative thereto about said axis shiftable elementsnormally proximal to the conveying mtanon h gnpper having an outer.surface means for cooperating therewith to shift a removed sheetqlsposed for fnctlonany e.ngagmg Sald one {marginal por- I tion of theend sheet as it is bent about said axis of the to said remote point, dcam means engageable with the shiftable elements and cargripper r meansfor driving said element in a direction to pull the end ried by saidshaft for moving the shiftable elements away from the conve in meansthrou h a dis 1 cement to Sheet .from h stack when the gripper reachesSheet y g g p releasing position. i the i Sheet thereigetween held bySaid i i 7. The feeder as set forth in claim 6, wherein said gripper isf romnmi thereof 0 t shaft as the carnage ls shiftable between an outerextended sheet-engaging location Shmeq from sald one end of its traveltoward the and an inner retracted sheet-releasing location insynchronism opposite endflereof for retummg the .Shlftable with theopening and closing of said line by said control mems to Posmonsproxlmfal to the fe means as mechanism, there being actuating meansengageable with said t gnppers approach release Posmonsi a Vacuumgripper for effecting extension thereof as the assembly is line; swungaway from said opposite marginal portion and the vacuum control valveapparatusconnectmg saldhne to the gripper rotated into saidSheehengaging position and rehab Shaft mounted on carnage and mcludmgtion thereof as the assembly is swung toward said opposite ctfmponemspresentmg a Compartment commumcatfng marginal portion and the gripperrotated into said sheetwiththe atmosphere and a passage leading from theline releasing position t 531d Shaft 8. In a feeder for flexible sheetmaterial: Said apparatus t being Ptovlded with a eohtro! Plate areceptacle for receiving and supporting a plurality of the movablycarried by the components and operable in first Sheets in Stackedrelationship; and second locations thereof to commun cate the shaft agripping assembly adjacent Said receptacle and provided with said andthe Compartment respectively; and with a gripper engageable in oneposition thereof with p means located to he engaged y the Plate dth'mgone marginal portion of the end sheet of the stack and reciprocation ofthe e to Shift the Plate from the 3 5 rotatable into a sheet-releasingposition about an axis first location thereof to the second location asthe carspaced f the end Sheet i the direction f f di riage moves fromsaid one position of the same to its h f; other Position and Vetsapowermeans operably coupled with the gripper for rotating 5. A feeder as setforth in claim 4, wherein the stop located the same about said axisbetween said positions and for IO effect shifting of the plate IO saidfirst location thereof is 40 simultaneously shifting the assembly andhence said axis movable to a disposition clearing the plate, andseiectively acgenerally toward the opposite marginal portion of the endtuatable means coupled to said movable stop for shifting the heet for asufficient distance to cause the gripped marlatter. ginal portion tobend about said axis away from the stack 6 In a feeder for flexiblesheet material: without moving the remainder of the end sheet, thereby areceptacle for receiving and supporting a plurality of the initiatingremoval of the end sheet from the stack;

sheets in stacked relationship; a conveying unit associated with saidgripping assembly and a gripping assembly adjacent said receptacle andprovided oscillatable therewith for completing removal of the end with agripper engageable in one position thereof with sheet from the stack,one marginal portion of the end sheet of the stack and said unitincluding a rotary element mounted on said rotatable into asheet-releasing position about an axis vacuum line for rotation relativethereto about said axis spaced from the end sheet in the direction offeeding of rotation of the gripper and having an outer surface thereof;disposed for frictionally engaging said one marginal porpower meansoperably coupled with the gripper for rotating tion of the end sheet asit is bent about said axis of the the same about said axis between saidpositions and for gripper; and simultaneously shifting the assembly andhence said axis means for driving said element in a direction to pullthe end generally toward the opposite marginal portion of the end sheetfrom the stack when the gripper reaches its sheetsheet for a sufficientdistance to cause the gripped marreleasing position. ginal portion tobend about said axis away from the stack h feeder as set forth in Claimwherein Said assembly without moving the remainder f the d Sheet, h band said unit are supported for oscillation together about a initiatingremoval of the end sheet from the stack, Second axis Spaced from theaxis of totatioh of the gripper ht said assembly being supported foroscillation about a i direction of feeding of the end Sheet Sat-d P Ymeans second axis spaced from the axis of rotation of the gripper belhgp r e to oscillate the g p about its 3x15 in ttmed in Said direction f fdi f the end Sheet, relationship w th oscillation of the assembly andthe unit about said power means being operable to oscillate the gripper531d second axlsabout its axis in timed relationship with oscillation ofsaid The feeder as Set forth elalm whereth Said PPe assembly about SaidSecond axis, vacuum-operated and wherein 15 provided control mechanismsaid gripper being coupled with a vacuum supply line for operably p ewtth 531d PP hp h Vacuuth P e vacuum-operation, there being controlmechanism e f the PP whet} the e e ls h the pp g operably Coupled withSaid gripper for providing vacuum positionthereof and for discontinuingsaid pressurewhen the pressure for the gripper when the latter is in theSheet gripper IS in the sheet-releasing position thereof, said controlmechanism being operable in response to said oscillation of the assemblyand the unit about said second axis.

a at t a m

1. A feeder for flexible sheet material comprising: a receptacle forreceiving and supporting a plurality of said sheets in stackedrelationship; a vacuum operated gripping assembly adjacent saidreceptacle and provided with a gripper engageable in one positionthereof with the marginal portion of an adjacent end sheet of the stackand rotatable through an arcuate path of travel into a sheet releasingposition to bend said marginal portion of the end sheet away from thestack without moving the remaining portion of the end sheet; a conveyingunit having a pair of opposed, relatively shiftable delivery elementsfor receiving a sheet therebetWeen at said releasing position of thegripper; power means connected to said gripper for rotating the samethrough said arc; and mechanism operably coupled to said gripperassembly and the conveying unit for controlling vacuum pressure to thegripper to cause said one marginal portion of the end sheet to begripped thereby at said one position of the gripper and to discontinuethe vacuum thereto at said release position thereof while actuating theelements in synchronism with said gripper rotation to effect withdrawalof the end sheet from the stack for advancement along a delivery path,said power means including drive structure operably connected to saidgripper assembly for raising and lowering the latter relative to saidstack, said power means being operable to oscillate the gripper betweenthe sheet-engaging and sheet-releasing positions thereof during raisingand lowering of the gripper assembly by said structure, there being avacuum line coupled to said gripper and adapted for connection to avacuum system, said mechanism including valve apparatus associated withsaid line and operated in response to raising and lowering of saidgripper assembly for opening and closing the line, said valve apparatusincluding a pair of opposed, relatively shiftable valve components, oneof said components being movable with said assembly during raising andlowering thereof, the other of said components being retainable in astationary disposition while said one component is shifted relativethereto to effect opening or closing of the line.
 2. The feeder as setforth in claim 1, wherein is provided an actuatable control systemassociated with said valve apparatus for maintaining the vacuum line ina closed condition upon malfunction of the gripping assembly, saidsystem including a solenoid adjacent the upper limit of assembly traveleffected by said drive structure and having a retractable plungernormally extended in disposition to engage said other component andretain the same as said one component continues movement with theassembly to open said line, and sensor means connected to said solenoidand operable to sense malfunction of the assembly and actuate thesolenoid to withdraw said plunger thereof to clear said other componentsuch that the latter is not retained by the plunger and no relativeshifting of the components occurs to open said line.
 3. The feeder asset forth in claim 2, wherein said control system further includes ablocking member mounted for shifting movement relative to said solenoidplunger and normally resting thereon, said member being disposed formovement into blocking relation with said plunger and engagement withsaid valve apparatus upon actuation of the solenoid to maintain theplunger in a withdrawn disposition such that said other component is notretained by the plunger.
 4. A feeder for flexible sheet materialcomprising: a receptacle for receiving and supporting a plurality ofsaid sheets in stacked relationship; a carriage rotatably mountedadjacent the receptacle for movement along a reciprocal path to causeone end of the carriage to move past a marginal portion of one end sheetof the stack thereof; a tubular shaft rotatably carried by the carriagefor pivoting about an axis parallel with and spaced from the axis ofrotation of the carriage; a series of spaced, vacuum operated hollowgrippers carried by the shaft in generally perpendicular relationshipthereto and communicating with the passage through the shaft; operatingmechanism coupled to the carriage and to the shaft for reciprocating thecarriage and oscillating the shaft in timed relationship; cam means onthe grippers and said carriage cooperable to shift the grippers intoextended first positions engageable with the marginal portion of saidend sheet of the stack when the carriage is at one end of its path oftravel away from the marginal edge of the end sheet and the shaft is indisposition with the grippers extendIng therefrom toward the stack, andto retract the grippers into sheet releasing positions in response tomovement of the carriage toward the marginal portion of the end sheetand rotation of the shaft through an arc to bend said marginal portionof the sheet gripped by the grippers away from the stack without movingthe remaining portions of the end sheet; movable conveying means carriedby the carriage and positioned to receive an end sheet removed from thestack and to transfer the removed sheet to a point remote from thereceptacle; shiftable elements normally proximal to the conveying meansfor cooperating therewith to shift a removed sheet to said remote point;cam means engageable with the shiftable elements and carried by saidshaft for moving the shiftable elements away from the conveying meansthrough a displacement to admit the end sheet therebetween held by saidgrippers during rotation thereof of the shaft as the carriage is shiftedfrom said one end of its path of travel toward the opposite end thereofand for returning the shiftable elements to positions proximal to theconveying means as the grippers approach their release positions; avacuum line; vacuum control valve apparatus connecting said line to theshaft, mounted on said carriage and including hollow componentspresenting a compartment communicating with the atmosphere and a passageleading from the line to said shaft, said apparatus further beingprovided with a control plate movably carried by the components andoperable in first and second locations thereof to communicate the shaftwith said line and the compartment respectively; and stop means locatedto be engaged by the plate during reciprocation of the carriage to shiftthe plate from the first location thereof to the second location as thecarriage moves from said one position of the same to its other positionand vice versa.
 5. A feeder as set forth in claim 4, wherein the stoplocated to effect shifting of the plate to said first location thereofis movable to a disposition clearing the plate, and selectivelyactuatable means coupled to said movable stop for shifting the latter.6. In a feeder for flexible sheet material: a receptacle for receivingand supporting a plurality of the sheets in stacked relationship; agripping assembly adjacent said receptacle and provided with a gripperengageable in one position thereof with one marginal portion of the endsheet of the stack and rotatable into a sheet-releasing position aboutan axis spaced from the end sheet in the direction of feeding thereof;power means operably coupled with the gripper for rotating the sameabout said axis between said positions and for simultaneously shiftingthe assembly and hence said axis generally toward the opposite marginalportion of the end sheet for a sufficient distance to cause the grippedmarginal portion to bend about said axis away from the stack withoutmoving the remainder of the end sheet, thereby initiating removal of theend sheet from the stack, said assembly being supported for oscillationabout a second axis spaced from the axis of rotation of the gripper insaid direction of feeding of the end sheet, said power means beingoperable to oscillate the gripper about its axis in timed relationshipwith oscillation of said assembly about said second axis, said gripperbeing coupled with a vacuum supply line for vacuum-operation, therebeing control mechanism operably coupled with said gripper for providingvacuum pressure for the gripper when the latter is in the sheet-grippingposition thereof and for discontinuing said pressure when the gripper isin the sheet-releasing position thereof, said vacuum line defining saidaxis of rotation of the gripper, said line being supported for rotationabout said axis and having the gripper mounted thereon for rotationtherewith; a conveying unit associated with said gripping assembly andoscillatable therewith for completing removal of the end sheet from thestack, said unit including a rotary element mounted on said vacuum linefor rotation relative thereto about said axis of rotation of the gripperand having an outer surface disposed for frictionally engaging said onemarginal portion of the end sheet as it is bent about said axis of thegripper; and means for driving said element in a direction to pull theend sheet from the stack when the gripper reaches its sheet-releasingposition.
 7. The feeder as set forth in claim 6, wherein said gripper isshiftable between an outer extended sheet-engaging location and an innerretracted sheet-releasing location in synchronism with the opening andclosing of said line by said control mechanism, there being actuatingmeans engageable with said gripper for effecting extension thereof asthe assembly is swung away from said opposite marginal portion and thegripper rotated into said sheet-engaging position, and retractionthereof as the assembly is swung toward said opposite marginal portionand the gripper rotated into said sheet-releasing position.
 8. In afeeder for flexible sheet material: a receptacle for receiving andsupporting a plurality of the sheets in stacked relationship; a grippingassembly adjacent said receptacle and provided with a gripper engageablein one position thereof with one marginal portion of the end sheet ofthe stack and rotatable into a sheet-releasing position about an axisspaced from the end sheet in the direction of feeding thereof; powermeans operably coupled with the gripper for rotating the same about saidaxis between said positions and for simultaneously shifting the assemblyand hence said axis generally toward the opposite marginal portion ofthe end sheet for a sufficient distance to cause the gripped marginalportion to bend about said axis away from the stack without moving theremainder of the end sheet, thereby initiating removal of the end sheetfrom the stack; a conveying unit associated with said gripping assemblyand oscillatable therewith for completing removal of the end sheet fromthe stack, said unit including a rotary element mounted on said vacuumline for rotation relative thereto about said axis of rotation of thegripper and having an outer surface disposed for frictionally engagingsaid one marginal portion of the end sheet as it is bent about said axisof the gripper; and means for driving said element in a direction topull the end sheet from the stack when the gripper reaches itssheet-releasing position.
 9. The feeder as set forth in claim 8, whereinsaid assembly and said unit are supported for oscillation together abouta second axis spaced from the axis of rotation of the gripper in saiddirection of feeding of the end sheet, said power means being operableto oscillate the gripper about its axis in timed relationship withoscillation of the assembly and the unit about said second axis.
 10. Thefeeder as set forth in claim 9, wherein said gripper is vacuum-operatedand wherein is provided control mechanism operably coupled with saidgripper for providing vacuum pressure for the gripper when the latter isin the sheet-gripping position thereof and for discontinuing saidpressure when the gripper is in the sheet-releasing position thereof,said control mechanism being operable in response to said oscillation ofthe assembly and the unit about said second axis.